Incontinence is a condition characterized by involuntary loss of urine, beyond the individual's control, that results from the loss or diminution of the ability to maintain the urethral sphincter closed as the bladder fills with urine. Male or female stress urinary incontinence (SUI) occurs when the patient is physically or emotionally stressed. One cause for this condition is damage to the urethral sphincter or loss of support of the urethral sphincter, such as can occur in males after prostatectomy or following radiation treatment, or that can occur due to pelvic accidents and aging-related deterioration of muscle and connective tissue supporting the urethra. Other causes of male incontinence include bladder instability, detrusor external sphincter dyssynergia (DESD), rescection of the prostate, over-flowing incontinence, and fistulas.
The female's natural support system for the urethra is a hammock-like supportive layer composed of endopelvic fascia, the anterior vaginal wall, and the arcus tendineus (a distal attachment to the pubic bone). Weakening and elongation of the pubourethral ligaments and the arcus tendineus fascia pelvis, weakening of the endopelvic fascia and pubourethral prolapse of the anterior vaginal wall, and their complex interaction with intraabdominal forces, are all suspected to play a role in the loss of pelvic support for the urethra and subsequent hypermobility to an unnaturally low non-anatomic position, leading to urinary incontinence.
In general, continence is considered to be a function of urethral support and coaptation. For coaptation to successfully provide continence, the urethra must be supported and stabilized in its normal anatomic position. A number of surgical procedures and implantable medical devices have been developed over the years to provide urethral support and restore coaptation.
Females can also exhibit cystocele, a condition due to laxity of the pelvic floor wherein the bladder extrudes out and downwards causing SUI. The severity of this bladder collapse is rated between Grades one through four. In Grade four cystocele, the bladder extrudes out of the vaginal opening. The treatment of choice for this condition includes the reduction or closing of the pelvic floor opening from which the bladder descends using sutures. Further surgical procedures and implantable medical devices have been developed to correct cystocele by supporting the bladder.
Currently, incontinence treatments of choice involve implantation of a Kaufman Prosthesis, an artificial sphincter (such as the AMS-800 Urinary Control System available from American Medical Systems, Inc.), or a urethral sling procedure in which a urethral sling is inserted beneath the urethra and advanced in the retropubic space, and perforating the abdominal fascia. Peripheral portions of the elongated urethral sling are affixed to bone or body tissue, and a central support portion of the elongated urethral sling extends under the urethra or bladder neck to provide a platform that compresses the urethral sphincter, limits urethral distention, and pelvic drop, and thereby improves coaptation.
Male and female urethral sling procedures are disclosed in commonly assigned U.S. Pat. Nos. 6,382,214 and 6,652,450, for example, and further female urethral sling procedures are described in commonly assigned U.S. Pat. No. 6,641,524, for example, and publications and patents cited therein. Implantation of certain urethral slings involves the use of delivery systems configured for and techniques that involve transvaginal, transobturator, supra-pubic and pre-pubic exposures or pathways.
In further surgical approaches disclosed, for example, in commonly assigned U.S. Patent Application Publication Nos. 2005/0043580 and 2005/0065395 (the entireties of each of these being incorporated herein by reference), elongated self-fixating urethral slings are implanted for treating female prolapse by use of a pair of sling implantation instruments or tools. The sling implantation tools comprise a handle with an elongated needle portion terminating in a needle distal end adapted to be coupled to free ends of the urethral sling and have mirror image right and left handed needle shapes. The sling implantation tools disclosed in the above-referenced 2005/0043580 publication have a curvature in a single plane and correspond generally to the BioArc™ SP and SPARC™ single use sling implantation tools sold by American Medical Systems, Inc., in a kit with an elongated urethral sling. The sling implantation tools disclosed in the above-referenced 2005/0065395 publication have a curvature in 3-dimensional space and correspond generally to the BioArc™ TO and MONARC™ single use sling implantation tools sold by American Medical Systems, Inc., in a kit with an elongated urethral sling.
In an exemplary sling implantation tool for females, the needle portion has a proximal straight portion extending from the handle and a distal shaped portion terminating in a needle distal end. The needle portion is sized and shaped so that the distal end may initially be moved through an abdominal incision adjacent to the obturator foramen and advanced along the posterior surface of one of the right and left posterior ischiopubic pubic ramus of the pelvic girdle spaced from the bladder. The advancement is continued toward the obturator membrane of the obturator foramen, through the obturator membrane toward the region of the patient's ischial spine, and then toward a vaginal incision in the region of the vaginal apex. The surgeon uses a learned wrist motion of the hand grasping the handle, and pressure feedback felt through the handle, to guide advancement. Also, the surgeon may palpate the vaginal wall with the fingers of the free hand to locate the needle tip and guide the tip toward and through the vaginal incision to expose the needle tip. The procedure is repeated using the other of the right and left hand sling implantation tools to advance the needle tip through a second skin incision and the other of the respective right and left obturator membranes to expose both needle tips through a vaginal incisions. In this way, right and left subcutaneous transobturator pathways are formed between the abdominal skin and vaginal incisions and extending through the right and left obturator foramen and connective tissue attached to the right and left posterior ischiopubic pubic ramus of the pelvic girdle. This procedure is preformed without visualization of the needle tip, and care must be taken to avoid deviating posteriorly and penetrating the bladder and to otherwise avoid damaging any of the obturator nerves, the superficial epigastric vessel, the inferior epigastric vessel, the external iliac artery and the internal iliac artery.
Right and left end portions of the elongated urethral sling are then drawn through the respective right and left tissue pathways as further described in the above-referenced 2005/0043580 and 2005/0065395 publications. Generally speaking, the free ends of the elongated urethral sling are each coupled to the needle distal ends, and end portions of the urethral sling are drawn through the pathways to draw a central support portion against the urethra to provide support. The free ends of the elongated urethral slings can include dilating connectors for connecting with the needle distal ends so that the pathways are dilated as the connectors are drawn through. The dilating connectors are drawn out through the abdominal skin incisions (lateral incisions) and are severed from the urethral sling. During the passage, a detachable protective sheath encases the right and left end portions, and the protective sheath is detached and withdrawn over the end portions exposing the urethral sling mesh to body tissue. The ends of the urethral sling may be optionally sutured to subcutaneous tissue layers. Tissue ingrowth into the mesh pores stabilizes the urethral sling chronically. Similar procedures for installing an elongated urethral sling to support the male urethra to alleviate incontinence are described in U.S. Pat. No. 6,652,450.
At least the proximal portions of the urethral sling are typically formed of an open pore mesh that is woven or knitted from mesh strands of a variety of biocompatible materials. The central support portion can also be formed of the same open pore mesh, and the central and end portions can be formed of a single elongated open pore mesh. Alternately, the central support portion may be formed of another material that is sewn to or otherwise attached to ends of the end portions. The portions of the urethral sling formed of open pore mesh can be fabricated by weaving or braiding or knitting a bolt of open pore mesh and then cutting strips of the appropriate length and width from the bolt. Cutting is carefully controlled to extend through the centers of mesh pores so that the edges of the end portions and the central support portion, if formed integrally with the end portions, constitute severed strands that would otherwise bound mesh pores.
A great deal of strain is placed on the end portions of the elongated urethral slings, causing them to stretch longitudinally as they are drawn through the pathways formed by the instruments. The open pores of the mesh of the proximal portions can become distorted in the process, such that pores may be narrowed or closed, inhibiting effective tissue ingrowth. Consequently, it has been found desirable to stabilize or tension the proximal portions to prevent undue stretching and elongation by adding at least one inextensible thread or tensioning suture extending from the central support portion to the free ends of the right and left proximal (“end”) portions. U.S. Pat. No. 6,652,450 describes a wide variety of resorbable or permanent tensioning sutures and techniques of fixing the tensioning suture to the open pore mesh of the right and left proximal portions.
The interaction of tissue with the severed strands along the sides of the end portions is also important in effecting fixation with tissue to maintain the appropriate tension of the central support portion against the urethra or bladder neck. It would be desirable for severed strands along edges of an implant to not become pressed out of the way, but remain extending outward and away from the intact pores of the open pore mesh. Consequently, it would be desirable to construct a urethral sling to advantageously maintain the shape of the urethral sling drawn through a tissue pathway and promote mechanical engagement with body tissue to aid in obtaining and maintaining tension.